<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<meta name="viewport" content="width=device-width, initial-scale=1.0">
		<title></title>
		<link rel="stylesheet" href="./Bootstrap4.6.1/css/bootstrap.css">
		<script src="./Bootstrap4.6.1/js/jquery.js"></script>
		<script src="./Bootstrap4.6.1/js/bootstrap.bundle.js"></script>
		<style>
			input{
				/* height: 50px; */
			}
			span{
				/* display: inline-block;
				height: 50px; */
			}
			.text{
				height: 100px;
				line-height: 100px;
			}
			
			.div01{
				width: 800px;
				height: 600px;
				line-height: 600px;
			}
			.form{
				width: 400px;
				height: 300px;
			}
			.div02{
				height: 300px;
				/* line-height: 300px; */
			}
			
		</style>
	</head>
	<body>
		<div class="clearfix">
			<input class="float-left" type="text" name="" id="">
			<span class="bg-danger text-white float-left d-inline-block d-lg-none">按钮</span>
		</div>
		
		<div class="border border-danger text text-center ">
			<!-- vertical-align: 相对于行内其他元素的垂直对齐方式;相对于行高的对齐方式 -->
			<span class="align-middle">垂直对齐</span>
		</div>
		<div class="div01 border border-info text-center">
			<form class="form bg-dark d-inline-block align-middle" action=""></form>
		</div>
		<div class="div02 border">
			<input class="align-middle" type="text" name="" id="">
			<span class="s2 d-inline-block h-75 bg-info">1111</span>
		</div>
	</body>
</html>